Tatsumi T, Jwa S C, Kuwahara A, Irahara M, Kubota T, Saito H
Division of Reproductive Medicine, Center of Maternal-Fetal, Neonatal and Reproductive Medicine, National Center for Child Health and Development, 2-10-1, Okura, Setagaya-ku, Tokyo 157-8535, Japan.
Comprehensive Reproductive Medicine, Regulation of Internal Environment and Reproduction, Graduate School, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-0034, Japan.
Hum Reprod. 2017 Jun 1;32(6):1244-1248. doi: 10.1093/humrep/dex066.
Are pregnancy and neonatal outcomes following letrozole use comparable with natural and HRT cycles in patients undergoing single frozen-thawed embryo transfer (FET)?
Letrozole use was significantly associated with higher rates of clinical pregnancy, clinical pregnancy with fetal heart beat and live birth, and with a lower rate of miscarriage, compared with natural and HRT cycles.
Letrozole is the most commonly used aromatase inhibitor for mild ovarian stimulation in ART. However, the effect of letrozole on pregnancy and neonatal outcomes in FET are not well known.
STUDY DESIGN SIZE, DURATION: A retrospective cohort study was conducted using data from the Japanese national ART registry between 2012 and 2013.
PARTICIPANTS/MATERIALS SETTING METHODS: A total of 110 722 single FET cycles with letrozole (n = 2409), natural (n = 41 470) or HRT cycles (n = 66 843) were included. The main outcomes were the rates of clinical pregnancy, clinical pregnancy with fetal heart beat, miscarriage and live birth. Adjusted odds ratios and relative risks (RRs) were calculated using a generalized estimating equation adjusting for correlations within clinics.
The rates of clinical pregnancy, clinical pregnancy with fetal heart beat, and live birth were significantly higher, while the rate of miscarriage was significantly lower in the letrozole group compared with the natural and HRT groups. In blastocyst stage transfers, the adjusted RRs for clinical pregnancy with fetal heart beat of letrozole compared with natural and HRT cycles were 1.48 (95% CI: 1.41-1.55) and 1.62 (95% CI: 1.54-1.70), respectively. Similarly, the adjusted RRs of letrozole for miscarriage compared with natural and HRT cycles were 0.91 (95% CI: 0.88-0.93) and 0.84 (95% CI: 0.82-0.87), respectively. Neonatal outcomes were mostly similar in letrozole, natural and HRT cycles.
Important limitations of this study included the lack of information concerning the reasons for selecting the specific FET method, parity, the number of previous ART failures, embryo quality and the dose and duration of letrozole intake.
These results suggest that letrozole use may improve clinical pregnancy, clinical pregnancy with fetal heart beat, and live births and reduce the risk of miscarriage in patients undergoing single FET cycles.
STUDY FUNDING/COMPETING INTEREST(S): No external funding was used for this study. There are no conflicts of interest.
Not applicable.
对于接受单胚胎冻融移植（FET）的患者，来曲唑使用后的妊娠及新生儿结局与自然周期和激素替代疗法（HRT）周期是否具有可比性？
与自然周期和HRT周期相比，来曲唑使用与更高的临床妊娠率、有胎心的临床妊娠率及活产率显著相关，且流产率更低。
来曲唑是辅助生殖技术（ART）中最常用于轻度卵巢刺激的芳香化酶抑制剂。然而，来曲唑对FET妊娠及新生儿结局的影响尚不明确。
研究设计、规模、持续时间：一项回顾性队列研究，使用了2012年至2013年日本全国ART登记处的数据。
参与者/材料、环境、方法：总共纳入了110722个单FET周期，其中来曲唑周期（n = 2409）、自然周期（n = 41470）或HRT周期（n = 66843）。主要结局为临床妊娠率、有胎心的临床妊娠率、流产率和活产率。使用广义估计方程计算调整后的比值比和相对风险（RR），对诊所内的相关性进行校正。
与自然周期组和HRT周期组相比，来曲唑组的临床妊娠率、有胎心的临床妊娠率和活产率显著更高，而流产率显著更低。在囊胚期移植中，来曲唑与自然周期和HRT周期相比，有胎心的临床妊娠的调整RR分别为1.48（95%CI：1.41 - 1.55）和1.62（95%CI：1.54 - 1.70）。同样，来曲唑与自然周期和HRT周期相比，流产的调整RR分别为0.91（95%CI：0.88 - 0.93）和0.84（95%CI：0.82 - 0.87）。来曲唑、自然周期和HRT周期的新生儿结局大多相似。
局限性、谨慎理由：本研究的重要局限性包括缺乏关于选择特定FET方法的原因、产次、既往ART失败次数、胚胎质量以及来曲唑摄入量和持续时间的信息。
这些结果表明，来曲唑使用可能改善接受单FET周期患者的临床妊娠、有胎心的临床妊娠及活产情况，并降低流产风险。
研究资金/利益冲突：本研究未使用外部资金。不存在利益冲突。
不适用。
